Lathe center



July z3, 1929.

H, D. DAVIS ET A1. 32h98 LATI-IE CENTER .Filed'may 23, 1927 2 sheetswsheef. l

'unglumg IDL. FCJWLEF July 23, 19.29. H, D, DAVls ET AL LATHE CENTER Filed May 23, 1927 2 Sheets-Sheet 2 H. D. navi-5 Y [1. L.. FEMA/1er" Patented July 23, 1929.

uNrrl-:uI STATES APATENT OFFICE.

HAROLD D. DAVIS AND CHARLIE L. FOWLER, OF ATHENS, TENNESSEE.

Application filed May 23,

ot' the invention resides in the provision of an improved type of dead center for lathes wherein the center )roper 1s revolubly mounted in anti-friction caring means for free ro` tation with th center.

A further object. of the invention is to provide a lathe center as set. forth embodying a construction whereby no adjustment due to wear is required. and embodying features whereby lubrication of the parts may be readily accomplished without the need `of special oiling n1 ans. i

A further object of the invention resides in the Lprovision of an "improved lathe center wherein av single roller bearing serves to carry both radial and thrust loads of a revoluble center proper.

A still further object of the invention is to provide an improved lathe center as defined which may be very economically manufac tured owing to the simplicity of the device, and one wherein lubrication is permitted merely by relative longitudinal movement of the lcenter proper with its carrying member.

Other objects and advantages of the invention will be apparent during the course of the following detailed description, taken in connection with the accompanying drawings forming a part of this specification and in which drawings:

Figure 1 is a side elevation of the preferred form of lathe center and ,showing the c enter proper withdrawn for its fullest extent of longitudinal movement from its carrier portion for permitting of lubrication of the roller bearing mounting for the center proper.

Figure 2 is a central longitudinal section through the lathe center as illustrated in Figure 1 and showing the parts in position during use of the center.

Figure 3 is a central longitudinal section through a slightly modified form of the invention and showing a two part construction for the shank or stem portion of the center proper.

Figure 4 is a transverse section taken substantially on the line 4 4 of Figure 2 and illustrating more particularly the construction of the outer end of the sleeve or carrier portion'for the center proper.

Figure 5 is a central longitudinal section through a further modified form of the ine work being supported by the LATHE CENTER.

1927. Serial No. 193,594.

vention and showing` a Islightly modified type of retaininguneans for the center proper.

Figure (5 a central longitudinal section showing a still further modified form of retaining means for the center proper.

Figure 7 is a centrallongitudinal section through a still further form of lathe center and showing "a slightly modified form of roller bearing mounting for the center proper.

Figure 8 is a transverse section on line 8%8 of Figure' G and looking in the direction of the arrows. r

leferring to the drawings in detail, and wherein` similar reference characters designate corresponding part-s throughout the several views. the improved lathe center is shown as embodying a main body or carrier portion A, a. center proper B,V a bearing C for revoluble mounting of the center proper within the carrir portion A, and a retaining means D for retaining the portions A and B in assembled relation and permitting limited rela tive longitudinal movement thereof.

Referring first to the preferred forni ot' the invention as illustrated in Figures l and 2, and more specifically' to the main body or carrier portion A, the same embodies a sleeve 10 having a rearwardly tapering external surface for fitting in the usual tail stock of the lathe. The outer end of the sleeve 1() is enlarged as at 11 and provided at its outer face with an annular pocket 12 having a reduced inner end for forming an internal annular shoulder 13 spaced slightly from the inner end of the pocket. Extending axially through the sleeve 10 and concentric with the annular pocket 127 is a circular bore 14 which extends from the pocket 12` to the inner Hat end face 15 of the sleeve.

Referring now to the center proper B, the sameembodies a conical shaped tip or head 16 and a spindle 17 which projects from the inner face of the head 16 in axial alignmentwith the center point 18. The spindle 17 is formed at its forward end with a bearing portion 19 being of a length substantiallyequal tothe depth of the pocket 12, and extending inwardly from the bearing portion 19 is a reduced stem or shank portion 2O of equal diameter throughout its length and which stem is of a length greater than the length of the bore 14 through Which the stem extends.

As willbe observed, the stem portion 2O is rotatably mounted within the bore of the sleev/e.

'10 and projects for a `substantial distance rearwardly pasttli'e end face 15 when the center proper B is in assembled relation with its carrier portion A.' Provided at the inner face ot' the head :16 and concentric with the axi'sof the bearing portion 19, is an annular groove 21 having. its smaller diameter greater than that of the bearing portion 19 for forming an annular abutment 22 encircling the outer end of the bearing portion 19. It is preferred that the conical tip or head 16 at its inner end bc of a diameter substantially equal to that of the enlarged sleeve portion 11 in order that the outer peripheral portion of the rear face of the tip will be disposed in confronting relation with the outer edge of the enlargement 11. As will be observed in Figure 2 the annular groove 21, when the portions A and B are in assembled relation` is disposcdin confronting relation with the annular pocket i 12 of the carrier portion A. Vhile such would appear obvious upon observing the drawings, it may here be well to state that the spindle 17 is formed as an integral part of the head 16.

Referring now to the bearing C for revoluble mounting of the center proper B within the carrier portion A, the same is of the usual roller bearing type and embodies companion inner and outer tapered braces 25 and respectively forming tracks for the cylindrical roller elements 27. The bearing C also embodies the usual retainer or spacer 28 for keeping the roller elements 27 evenly spaced and in line with the tracks formed by the races 25 and 26. This bearing C by reason of the tapered tracks of the races 25 and 26 serves as a combined thrust and radial bearing for the load carried by the center proper B, and as will be observed in Figure 2, the races 25 and 26 are arrangedy so that the axes of the rollers 27 extend in diverging relation toward the center point 18. The inner race 25 is of a width slightly less than the length of the spindle bearing portion 19 and is mounted on the bearing portion 19 by means of a wedging lit and abuts at its outer end the annular abutment 22. This pressed fitting of the race n i l i 25 upon the bearing portion 19 will cause the race to turn with the center proper B and in which pressure upon the head 16 is transmitted to the race 25 by means of the annular abutment 22. The outer race 26 is pressed into the annular pocket 12 with its inner edge abutting with the annular shoulder 13, and which annular shoulder 13 serves to prevent inward movement of the race 26 due to the inward pressure exerted on the' race by means of-the roller elements A27. The retainer or spacing ring 28 and which serves t'or retaining the rollers 27 assembled upon the inner race 25 when the carrier A is removed from the center proper B, projects at its outer edge for a short distance into the annular groove 21 and for a purpose to be subsequently ex- By so having the retainer or spacing ring 28 project at its outer edge for a short distance into the annular groove 21, such serves as means for conveying thc lubricant in the groove 21 to the rollers 27, and by reason of the ring spanning the space between the rear face of the head 16 and forward edge of the carrier A, such will prevent foreign matter such as cuttings from the lathe tool from readily entering the annular groove 21 and eventually working into the races for the roller bearings.

By observing Figure 2 it will be seen that when the carrier portion A is moved outwardly along the stem 20 until the outer race 26 properly engages the rollers 27, that a small A,clearance is provided between the rear edge of the head 16 and forward edge of the sleeve enlargement 11. This small clearance space between the portions A and B will practically exclude entrance of any foreign matter into the roller bearing C when the lathe center is in use.

Referring now to the retaining means Dl for securing the sections A and B in assembled relation, and more particularly to the form of retaining means for the type of lathe center as illustrated in Figures 1 and 2, the same consists of a` washer 30 held against longitudinalmovement off the inner end of the stem portion 20 by means of a suitable Cotter pin or key 31. This cotter pin 31 extends through the stem 20 at a location whereby a suitable clearance such as at 32 in Figure 2 is provided between the washer 30 and the end face 15 of the sleeve 10 when the'center proper B is in operative relation with the carrier portion A. 4This spacing of the washer 30 permits of slight relative longitudinal movement of the sections A and B, and when the center proper is withdrawn for its limit of longitudinal movement as illustrated in Figure 1, sufficient clearance is provided between the rear edge of the head 16 and enlargement 11 for the positioning of a lubricating grease within the annular groove 21 for lubrication of the roller bearing C. Thus it will be seen that the means D aside from retaining the sections A and B in assembled relation, is so positioned as to permit of slight relative longitudinal movement of the sections A and B for allowing lubrication of the bearing C.

With reference to the form of lathe center as illustrated in Figure 3, the sleeve 10 has its bore 111 enlarged at its outer end as at 34 for revolubly receiving the stub shank 20 of the center proper B. This stub shank A proximatel lagainst movement off the a suitable Cotter' pin 31. The bore 35 of the 20 and which as will be observed is of apone-half the length of the sleeve 10, is provided at its inner end with a threaded bore for receiving the threaded inner end 13 vof a stem 37 which extends through the bore 14 vwith its end extending past the inner end face of the sleeve. Mounted on the projecting portion of the stem 37 and spaced from the inner end face of the sleeve, is a retainingr means as illustrated in Figures 1 and 2 and embodying a .washer 30' held stein by means of stub shank 20 is of a depth so that when the stem 37 is threaded into the bore the washer 30 will bespaced sufficient distance from the inner end of the sleeve 10 as to prevent possible locking of the center proper within the carrier A and also allow for relative longitudinal movement of the sections A and B for a purpose as defined in the construction of the form of lathe center as illustrated in Figures 1 and 2.

With the form of lathe center as illustrated in Figure 5, the retainin means D is in the form of a cap screw cm odying a head 40 and a shank or stem portion 41 having a threaded end for threaded connection within the threaded bore 35 of the stub shank 20. The shank or stem 41 is ofsuch length that the head 40 is spaced from the inner end face 15 of the sleeve 10, and a roller bearing 42 is preferably mounted on the stem 41 between the head 40 and end face 15 for allowing free rotation of the member D when moved outwardly of the member A. It will also be observed that relative longitudinal movement of the members A and B is permitted by the spacing provided between the end face 15 and the bearing 42.

Vith the form as illustrated in Figure 6, the bearing 42 has been omitted and the sh ank 41 of the cap screw shortened so that when the inner end of the shank 41 is threaded into the bore 35 for its fullest extent, the head 40 will bespaced from the end face 15 for allowing relative .longitudinal shifting of the members A and B.

By so having the central portions as illustrated in Figures 3, 5 and 6 of two piece construction, such will permit of more economical manufacture of the lathe centers since less stock is lost in machining the center proper B by reason of forming the shank portion of a length considerably less than the full length of the carrier portion A.

y Vith the form of lathe center as illustrated in Figure 7 the bearing C is of the double roller bearing type with one portion of the bearing extending into the annular pocket 12 of the member A, and the head 16 havin an annular pocket 45 provided in the rear ace for receiving a portion of the double roller bearing.

From the foregoing description it will be apparent that a novel and improved type of., lathe center has been provided wherein the center proper is revolubly mounted in antifriction bearing means for free rotation with the work being supportedby the center, one wherein lubrication is permitted by reason of relative longitudinal movement of the center proper with its carrier portion and which longitudinal movement eliminates possibility of the center proper and its carrier member to have a tendency to become locked with one another, and one wherein a single protected roller bearing serves to carry both radial and thrust loads of the revoluble center proper.

Various changes in the shape, size and arrangement of parts may be made to the Specie forms of the invention herein shown and described, without departing from thevspirit of the invention or the scope of the following claims.

lVe claim:

1. A lathe center comprising a tubular carrier portion having a pocket opening at its outer end, a center proper including a head having an annular groove 1n its inner face in confronting relation to said pocket and a spindle rotatable in the carrier portion, an anti-friction roller bearing arranged in said pocket for revoluble mounting of the center proper in the carrier portion and including a retaining ring having its outer edge projecting slightly into said annular groove, and means for retaining the center proper in position within the carrier portion and permitting free limited movement of the center head away from the outer end of the carrier portion'. v

2. A lathe center comprising a tubular car--- rier portion having a pocket opening at its outer end, a center proper including a head havingan annular groove provided at its inner face in confronting relation to said pocket and a spindle rotatable in the carrier portion, said head having its inner face slightly spaced from the outer end of the carrier portion. an anti-friction roller hearing for revoluble mounting of the center proper in the carrier portion, including an outer race secured in the pocket of the carrier portion,` an` inner race carried bv the center spindle, roller elements between the races, and a retaining ring for the rollers movable with the inner bearing race and having its outer edge projecting for a short distance into the annular groove of the center head, and means for retaining the carrier portion and center proper in assembled relation and allowing limited relative longitudinal movement thereof.

3. A lathe center comprising a tubular carrier portion having apocket opening at its outer end, an outer bearing race lixed in the pocket, a center proper including a head having an annular groove provided in its inner face in confronting relation to said pocket and a spindle rotatable in the carrier portion,

said spindle including a bearing port-ion adjacent said head, an inner bearing race rigidly carried by the bearing portion, roller elements ar anged between the inner and outer bearing races for normally retaining the center head slightly spaced from the outer end of the carrier portion, said roller elements having their axes extending in diverging relation toward the-center head point, a retaining ring for the roller elements and projecting slightly into the annular groove of the center head, and retaining means for the carrier portion and center proper-for retaining the same in assembled relation and permitting limitedv free outward movement of the center head for increasing the spacing between the head and outer end of the carrier portion.

4. A lathe center comprising a tubular carrier portion having a pocket opening at its outer end, a center proper including a head having its inner face in confront-ing relation to said'pocket and a stem portion rotatable in the carrier portion and projecting past the inner end face thereof, an anti-friction roller bearing arrangement in said pocket for revoluble mounting of the center proper in the carrier portion Withthe center head spacedy slightly from the outer end of the carrier portion, and a retaining means carried by the rearwardly projecting end of the spindle and spaced from the inner end face of the carrier portion for allowing limited outward movement of the center proper with respect to the carrier portion.

A 5. A lathe center comprising a tubular carrier portion having a pocket opening at its outer end, a center proper including a head having its inner face in confronting relation t0 said pocket and a stein portion rotatable in the carrier portion and having a threaded bore at its inner end, an anti-friction bearing arranged in said pocket for revoluble n1ounting of therenter proper in the carrier portion against radial and thrust loads, a shank having threaded connect-ion with the bore of said stem and projecting past the inner end face of the carrier portion, andan abut-ment carried by the shank in spaced relation 'from the inner end of the-carrier portion for allowing limited outward movement of the center proper with respect to the carrier portion.

6. A lathe center comprising a tubular carrier portion having a pocket opening at its outer end, a center proper includinga head having its inner face in `confronting relation to said pocket and a shank portion extending into the carrier portion and having a threaded socket at its inner end, an anti-friction roller bearing arranged in said pocket for revoluble mounting of the center proper in the carrier portion with the center head spaced relatively close to the outer end of the carrier portion, and means for retaining the center proper in assembled position with the carrier portion and permitting for slight movement of the center head away from the outer end of the carrier portion, comprising a cap screw including a head normally spaced from the inner end of the carrier portion and a stem having threaded connection at its inner end in the bore of said shank.

HAROLD D. DAVIS. CHARLIE L. FOWLER. 

